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Facebook Q&A Session 2nd November


Thompson & Morgan Facebook Q&A Session 2nd November - Your horticultural questions answered.

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Name: Bob Moore

Question: I've ordered quite a lot of perennial seeds this year, and fairly inexperienced. What size do the plants need to be for me to nip them, to make them bushy? Also, when I've grown the plants on, do I plant them out next year, or leave them until the spring of 2014?

Answer: Hi Bob. It’s great to hear that you are growing your own perennials. If you have sown some already then make sure that you don’t overwater them during the winter months - they won’t do a lot of growing while the temperatures and light levels are low. If they get too cold and wet then you run the risk of the seedlings rotting off.

You don’t need to worry about pinching out their stems until they are potted up individually and growing strongly. They will probably be getting on for about 10 to 15 cm tall (5-6") by the time that pinching becomes necessary. Simply pinch the main stems back between your finger and thumb to just above a node. This will encourage new stems to break further down the stem and make bushier plants.

You could plant your young perennials out in late spring/ early summer next year, but bear in mind that they will still be quite small and may succumb to competition from larger plants. It might be better to grow them on until next autumn to make bigger, more substantial plants. You will need to pot them on into progressively larger pots as they grow. You can plant them out in October or November 2013, and this should give them sufficient time to settle in to their new homes before the following growing season. Hope that helps you Bob. Let me know if you have any more questions.

Name: Farooqui Yawar

Question: Hi, I got few seeds like poppy, Heliopsis, Geranium etc. It’s sowing time for annuals in India. Can I save few seeds for next year? Will it decrease its germination rate? Thanks

Answer: Hello Farooqui. Yes you can save some seeds if you want to. The germination rate may decrease slightly but all of the seed that you mention should last for a few years. Make sure that you store them in a cool, dry place. You can also collect some seed from the plants that you grow this year if you want too.

Name: Farooqui Yawar

Question: Hi Sue, I have Heliopsis scabra ‘Golden Double Hybrid’. On the seed pouch germination time is 1 to 3 month but in the seed catalogue it is 20 to 30 days. A contradiction there. Please tell me which is right.

Answer: Hi Farooqui. The seed packet is correct - your Heliopsis seed should germinate within about 30 days. We will amend our website to show the same information. Many thanks for pointing this mistake out to us.

Name: Katrina Downs-Rose

Question: Hi. Can you tell me which variety of parsnip is best suited to a short growing season? Thanks.

Answer: Hi Katrina. Most Parsnips need a really long growing season to make decent sized roots but there are a few summer varieties that have been specially bred to mature quicker and can be harvested as mini-vegetables. Parsnip ‘Arrow’, Parsnip ‘Dagger’ and Parsnip ‘Lancer’ are all worth growing. They will produce bayonet shaped roots, about the size of a large carrot, which can be harvested from July to August.

Name: Anna Mason

Question: Hiya I have just taken all the geraniums out of their containers and I am loathe to throw them away. How best to overwinter please. I also have some wax begonia bedding I would like to keep. I have a small greenhouse but that is stuffed with Fuchsias. My options are garage, shed or conservatory.

Answer: Hi Anna. When you refer to geraniums I am assuming that we are talking about Pelargoniums rather than hardy geraniums. These can be overwintered, but they will need a bright location with a minimum temperature of 5C (41F). Your conservatory is probably the best spot for them.

Pot them up individually and cut the stems back to about 10cm (4"). During winter they will need very little water - keep the compost barely moist. When the weather begins to improve in spring you will start to see small signs of growth and this is your cue to gradually increase watering. You can also give them a general purpose feed in spring to encourage strong growth. Remember that you will need to harden them off again before moving them outside next year. The begonias will need similar treatment, although you probably won’t need to cut these back. Best of luck with them, Anna. Looks like you may need to ask for a bigger greenhouse for Christmas this year!

Name: Jackie Mason

Question: Hi Sue, I have Cambria orchid which seems to have small scale insects on the leaves. Any thoughts please on what these are and what I should do about them. At the moment, I scrape them off. They don't seem to affect the plant as it is flowering well.

Answer: Hi Jackie. Unfortunately scale insect can be tricky to eliminate as the adults form hard waxy shells that act as a protective armour.Worse still, on indoor plants the warm environment allows them to continue reproducing all year round.

The key thing to remember with scale insects is that they are relatively immobile, so infestations are normally brought in when new plants are introduced. This can be avoided by giving all new plants a thorough inspection, regardless of how reputable the supplier is! Use a magnifying glass and check every part of the plant. Scale insect occurs on all parts, so check the stems as well as the leaves. It would also be best to quarantine any new plants on a different windowsill for a month to check that they are not carrying scale insects. The moment that you suspect a problem you must remove the plant to prevent scale insects from spreading.

To combat the current problem on your orchid, you will need to use different methods of attack for the adults and the juveniles. Scrape the adults off of the plant with your thumb nail and wipe the foliage and stems gently with a cloth dipped in soapy water. Chemicals are most effective on the crawlers (juvenile forms) as they are more vulnerable before they develop a hard shell. Try products with the active ingredients of thiacloprid (e.g Provado Ultimate Bug Killer), acetamiprid (Scotts Bug Clear Ultra) or thiamethoxam (Westland Plant Rescue Bug Killer Ornamental Plants). You will need to make a repeat application two weeks later in order to catch any that you missed first time. Make sure you spray the underside of the leaves and the stems too, but avoid sprayiong the blooms as this may cause them to drop. It is worth knowing that the dead adults do not drop off of the plant which makes it difficult to spot new infestations. Best of luck Jackie.

Name: Mo Coleman

Question: Hi Sue, I have inherited some raspberry canes but don't know which canes fruited this year or the variety. What should I do about cutting back? Thanks

Answer: Hi Mo. There are two questions that we need to answer - firstly are they summer or autumn fruiting varieties, and secondly, if they are summer fruiting varieties, which are the young stems that will fruit next year?

The easiest way to tell autumn and summer varieties apart is to wait until they fruit. The main distinguishing features of Autumn fruiting varieties is that they will fruit over a long period from August to October, or even into November. Autumn fruiting raspberries tend to be more self supporting than summer fruiting varieties with shorter, stiffer, more upright growth. They will produce fruit all the way up the cane and not just at the tops. If any are currently showing evidence of fruiting then these are likely to be autumn fruiting varieties. These plants can be cut back to ground level in February. They will produce new stems next spring and these will carry next year’s crop.

In contrast, summer fruiting varieties have more lax, sprawling growth. If the plants are trained onto a post and wire framework, then these are likely to be the summer fruiting raspberries. Your best bet is to prune out all of the older, woodier stems. The younger stems will be more flexible, less woody and the stems are likely to be greener rather than brown. These younger stems can be tied onto the post and wire framework to produce next year’s crop.

If you are still unsure then you can always prune all of your raspberry canes back to 7cm (3") above ground level in February. Don’t worry about getting it wrong. The worst that can happen is that you will miss out on next years crop from any summer fruiting canes. It may even do them some good, particularly if they have been neglected in previous years. Best of luck with them.

Name: Jonathan Pollard

Question: Hi Sue, I have ivy covering a fence at the back of the garden which acts as a screen between us and neighbours. Over the past couple of years it has really grown outwards and is taking a lot of light. I want to prune it back. When is the best time to do it? Can I prune quite hard and how long is it likely to take fill with leaves again?

Answer: Hello Jonathan. Ivy is normally quite resilient but its best to leave pruning until early spring, just before the new growth starts. You can trim all of the outward and upward growing stems back a healthy bud within the main canopy of the plant. This will help to disguise the cuts. If it is really overgrown then you might want to cut the plant right back to just a 1m (3’) above ground level. Ivies tend to respond very well to such hard pruning but it will take a couple of growing seasons for them to fully grow back. If you do decide to hard prune your Ivy then I would recommend that you give it a good feed afterwards. Hope that helps.

Name: Daniel Stewart Marshall

Question: Hi Sue, I planted a load of allium bulbs the other week and covered the ground with big clumps of forget me not, thinking the combination would look nice at the allotment. However, worried now the little bulbs won't push through the roots come spring, am I worrying unnecessarily?

Answer: Don’t worry Daniel - they will find their way up through the soil surface. If the clumps of Myosotis are enormous then you could divide them into smaller clumps but I doubt that this will be necessary. Plants are surprisingly adaptable and can normally manage very well without our help.

Name: Elaine Leiper

Question: Can anyone tell me what the small white millepede type creatures are (about 3cm long), that tunnel into my strawberries, taters and just about any other root crop I plant? They are abundant in my veggie patch and can find as many six tunnelled into strawberries, apart from turning my stomach they do a lot of damage too.

Answer: Oh dear Elaine. It sounds like you are dealing with spotted snake millipedes (Blaniulus guttulatus). These little pests usually stick to decaying plant matter. However they do tend to enlarge any wounds that have been created by another pest, such as slugs or snails. They are particularly partial to a few plant species including strawberry fruits, potato tubers and carrots. They also quite enjoy eating tiny seedlings and the damage is always caused either at soil level or below ground.

They prefer a soil that is rich in organic matter, and enjoy accumulations of undisturbed decaying plant material, so thorough digging and good garden hygiene is often enough to control the problem and reduce their population.

Given that they are generally a secondary pest, colonising wounds made by other pests, it is often most effective to control the pest that causes the initial damage rather than the millipedes. My guess is that the damage was most likely caused by slugs or snails which have been particularly prevalent this year. Try to control these next year with slug pellets or nematodes and this should help to reduce damage to your crops.

Name: Elaine Leiper

Question: Was thinking about buying the dwarf cherry tree Griotella but was put off by the description that the cherries are sharp tasting, can anyone tell me if they are sweet enough to eat raw and am I indeed likely to get any in the cold, wet climate of Inverness in the highlands of Scotland?

Answer: Hello Elaine. Cherry ‘Griotella’ produces cooking cherries that are suitable for using in desserts, sauces and other recipes. But this is not a variety that you would pick and eat straight from the tree. Cherry Sunburst or Cherry ‘Stella’ might make a better choice if you are after a dessert cherry. If grown in a sunny, sheltered position, any of these cherries should produce fruit successfully in Inverness.